Curved foil above the fourdrinier wire

ABSTRACT

A curved foil member is positioned above the paper web extending transversely across the width of the web and is adjustably supported. A shower head is mounted on the foil support to clean the leading edge of the foil member. The foil member squeezes the web from above and forces air which has been entrained immediately above the path of the moving web down through the web to create a dewatering force.

United States Patent Thomas G. McKie Inventor Beloit, Wis. Appl. No.798,889 Fi1ed Feb. 13,1969 Patented Dec. 21, 1971 Assignee BeloitCorporation Beloit, Wis.

CURVED FOIL ABOVE THE FOURDRINIER WIRE 6 Claims, 5 Drawing Figs.

[1.8. CI 162/312, 162/210, 162/361 Int. Cl D211 7/00 Field of Search162/312, 344, 347, 210, 205, 305, 361, 374, 308, 311, 313, 314

References Cited UNITED STATES PATENTS 1,814,268 7/1931 Sweeney 162/3132,170,109 8/1939 Berry .1 162/352 2,441,169 5/1948 Roman.. 162/3142,779,252 1/1957 Welz 162/361 2,888,378 5/1959 Maguire 162/313 3,010,5101 1/1961 Cirrito 162/344 3,477,905 11/1969 Rogers 162/305 PrimaryExaminer-S. Leon Bashore Assistant ExaminerRichard H. AndersonAttorney-H111, Sherman, Meroni, Gross & Simpson ABSTRACT: A curved foilmember is positioned above the paper web extending transversely acrossthe width of the web and is adjustably supported. A shower head ismounted on the foil support to clean the leading edge of the foilmember. The foil member squeezes the web from above and forces air whichhas been entrained immediately above the path of the moving web downthrough the web to create a dewatering force.

, 1 CURVED FOIL ABOVE THE FOURDRINIER WIRE BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates topapermaking machines and in particular to apparatus for removing waterfrom a traveling paper web.

2. Description of the Prior Art The most generally used processes formaking paper, for example. the Fourdrinier process, employs a relativelyheavy transporting medium, such as water, for carrying paper stockfibers along the path of equipment which forms a papermaking machine. Inthe wet section of the papermaking machine the mixture of water andpaper stock fibers are deposited as a flowing liquid sheet on a movingporous or perforate supporting surface, usually called a forming wire,at the same speed as the speed of the forming wire. At this point themass of the paper web so formed is almost totally water by weight.

It is desirable to remove the water from the traveling web for severalreasons. Of course, paper products are usually dry and it is necessaryto remove the water to provide a dry product. In addition, inasmuch aswater is a relatively heavy medium, heavymachinery is required forsupporting and moving the traveling web; therefore, removal of the waterearly in the process would permit the utilization of lighter supportingstructures by relaxing the design criteria for such equipment. Also, thetotal drying process would be decreased.

The correctional methodof removing water from the web begins with theapplication of a vacuum, through the medium of suction boxes, below theforming wire to draw water from the web. The method then squeezes waterfrom the web by passing the web through-pressing rollers. Blotting thewet web by continuously running felts is also employed as is passing theweb over heated rollers to evaporate water therefrom. The dryingrequirements of each would be decreased if techniques immediatelydownstream of the point of deposition or initial web formation can beimproved.

It is therefore the object of the present invention to provide animproved method and means for removing water from a traveling paper webwhile on the Fourdrinier wire.

Another object of the invention is to permit the utilization of lighterstructures in a papermaking machine for supporting a traveling web.

Another object of the invention is to remove water from a travelingpaper web at a point immediately downstream of the point of webformation.

A still further object of this invention is to decrease the dry ing timerequired in making paper.

SUMMARY OF THE INVENTION According to the present invention, and infulfillment of the above objects, additional amounts of water may beremoved from the traveling web as it is carried on the perforate formingsurface by advantageously utilizing the flow of air immediately abovethe web created by the movement of the web to establish through theconstruction of such airflow, a pressure for forcing water from the web.According to the invention, a foil above the web is used which squeezesthe web from above; also a constriction of airflow is accomplished bythe provision of a curved foil member immediately above the surface ofthe traveling web having a generally downwardly directed foil surfacewhich extends transvcrsely across the width of the web. The air passingbetween the foil member and the traveling web creates a pressure abovethe surface of the web for effecting removal of water in the web throughthe perforate supporting surface.

BRIEF DESCRIPTION OF THE DRAWINGS The invention, its organization andconstruction will be best understood by reference to the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. I is an elevational and schematic illustration of a Fourdriniertype papermaking machine and process incorporating the principles of thepresent invention;

FIG. 2 is an elevational and schematic illustration of a portion of apapermaking machine and process employing the foil apparatus of thepresent invention positioned immediately downstream of the slice of thehead box;

FIG. 3 is an elevational view of a papermaking machine showing amodification of the foil apparatus of FIG. 1;

FIG. 4 is an elevational view of the foil apparatus of the presentinvention; and

FIG. 5 is an elevational view of another foil apparatus of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. I shows, in fragmentarysection, a head box 10 including a forward wall 11 and a bottom wall 12forming a slice for the deposition of stock material onto a travelingporous, or perforate, surface 13, as is well known in the papermakingart. The perforate surface 13 is usually in the form of a continuous orendless forming wire which travels a circuit including supporting roller14. Below the perforate surface are deposed a plurality of suction boxes16, 17 and 18, as is commonly practiced, to aid in removing water fromthe traveling web. As the web travels at a predetermined speed, an aircurrent is established immediately above the surface of the travelingweb. This flow of air is advantageously utilized in practicing thepresent invention to remove water from the traveling web. To this end, afoil apparatus 19, is positioned immediately above the surface of thetraveling web to constrict the aforementioned flow of air and establisha pressure in the area of constriction to effect a removal of waterdownwardly through the web and its supporting surface 13. The foilapparatus 19 comprises a curved foil member 21 which extends generallydownwardly and in the direction of web travel and further extends acrossthe web in its transverse direction, the curved foil member 21 beingsupported by one or a plurality of supporting members 20 which aremounted for both longitudinal and vertical adjustment as indicated bythe set of double-headed arrows 22. The curved foil member 21 and theupper surface of the traveling web form an air passage of decreasingcrosssectional area between the leading and trailing edges of member 21.The air flowing above the surface of the web is therefore constricted inthis area to create a pressure for removing water from the travelingweb.

FIG. 2 also illustrates a head box 10 having a forward wall 11 and abottom wall 12 which form a slice opening for the deposition of paperstock onto a traveling forming surface 13 which traverses a circuitpartially defined by roller 14. In this particular illustration, amultiple-inlet suction box 28 is provided below the forming surface 13immediately downstream of the head box. Also, immediately downstream ofthe head box. Also, immediately downstream of the suction box 28, acurved, downwardly sloping foil member 21 is positioned above thesurface of the traveling web. As in FIG. 1, the curved foil member 21 issupported by a support member (or members) 20 which is mounted forlongitudinal and vertical adjustment, as again indicated by thedouble-headed arrows 22. Further, mounted on the support member 20 is ashower head 23 directed to clean the leading edge of the curved foilmember 21. Positioned immediately downstream of the foil apparatus 19 isa deflector 27 for deflecting water flowing from the underside of theforming surface 13.

FIG. 3 illustrates the foil apparatus 19 and its cooperating deflector27 being disposed immediately before the couch roll 15 of thepapermaking machine. In FIG. 3 the head box I0 is further shown asincluding adjusting apparatus 31 for changing the size of the sliceopening, and further shows that the traveling web leaves the circuit ofthe forming surface at couch roll 15, as indicated by the reference W.In some instances it may be to advantage to employ the foil apparatus atseveral locations along the traveling web. For example, a foil apparatuspositioned as shown in both FIGS. 2 and 3 may be advantageously utilizedfor certain paper types.

FIG. 4 illustrates an adjustably mounted foil apparatus having a foilmember 21 and a supporting member 20 carrying a shower head 23, the foilapparatus being adjustable longitudinally and vertically, as indicatedby the double-headed arrows 22. Further, the foil apparatus is pivotallymounted on a shaft 24 for arcuate movement thereabout. as indicated bythe curved double-headed arrow 25. This full range of availableadjustments permits positioning of the curved foil member 21 at anydesired position and at any desired angle with respect to the travelingweb.

FIG. illustrates a foil apparatus having a supporting member to which isattached a foil member having a convex surface 29 toward its leadingedge and a concave surface 30 at its trailing edge. The curvature ofsurface 30 provides an additional constriction of airflow by directingthe trailing edge of the foil downward to additionally throttle theairflow at the trailing edge and create an increase in pressure forremoving water from the traveling web.

Although I have described my invention by reference to certainillustrative embodiments herein, it is to be understood that manychanges and modifications of the invention will become apparent to thoseskilled in the art and such changes and modifications should be includedin the spirit and scope of my invention as set forth in the appendedclaims.

What I claim as my invention:

1. In a papermaking machine, the combination comprising a poroustraveling forming surface;

means for depositing a flow of stock containing water and paper fibersonto the traveling forming surface to form a traveling web,

said traveling web effecting a flow of air along its upper surface;means beneath the porous forming surface for receiving water from theweb formed on the forming surface; and

a stationary foil member disposed above the traveling web and extendingtransversely across the web and including a lower curved surface slopingdownwardly toward the upper surface of the web and including a leadingand trailing edge and extending at its trailing lower edge in closerunning relation thereto, said surface being at an acute angle to theoncoming web and being of substantial length in the machine directionsufficient to capture the layer of air traveling with the moving web andto establish a downward dewatering pressure in the area where thesurface is in close running relation with the web to aid in forcingwater down through the web and through the porous surface.

2. In a papermaking machine in accordance with claim 1 wherein the angleof the lower surface of said foil member is adjustable relative to theupper surface of the web.

3. In a papermaking machine in accordance with claim 1 including a waterspray positioned in advance of said foil member for directing wateragainst the leading portion of the foil member.

4. in a papermaking machine in accordance with claim 1 wherein said foilmember is carried on a support pivotally mounted above the foil memberand said support is adjustable about its pivotal point.

5. In a papermaking machine in accordance with claim 1 wherein the lowersurface of the foil member has a convex curvature on its leading edgeand a concave curvature on its trailing edge.

6. In a papermaking machine in accordance with claim 1, wherein the foilmember is positioned immediately downstream of the point of stockdeposition onto said forming surface.

IF i I I I!

2. In a papermaking machine in accordance with claim 1 wherein the angleof the lower surface of said foil member is adjustable relative to theupper surface of the web.
 3. In a papermaking machine in accordance withclaim 1 including a water spray positioned in advance of said foilmember for directing water against the leading portion of the foilmember.
 4. In a papermaking machine in accordance with claim 1 whereinsaid foil member is carried on a support pivotally mounted above thefoil member and said support is adjustable about its pivotal point. 5.In a papermaking machine in accordance with claim 1 wherein the lowersurface of the foil member has a convex curvature on its leading edgeand a concave curvature on its trailing edge.
 6. In a papermakingmachine in accordance with claim 1, wherein the foil member ispositioned immediately downstream of the point of stock deposition ontosaid forming surface.